The purpose of this proposal is to determine the possible role of isopeptidases that regulate the ubiquitin induced degradation of the cell cycle and proapoptotic regulatory proteins P27 and P53 in prostate cancer. In order to determine the function of this isopeptidase system, they will perform the following specific aims: 1) Utilizing a high throughput in situ hybridization and immunohistochemistry technique, they will assess the expression of P27 and P53 mRNA and protein in normal and malignant human prostate epithelium. Expression will be assessed in prostate tumors of various grades and metastatic abilities. In order to accomplish this task the investigator has established a large 3 site tissue collection system that will provide high quality tissue for these studies. From this first aim, a sunset of cases will be selected to further examine ubiquitin proteasome degradation specific for p27/p53. This will be on the basis of increased or no change in mRNA, but decreased protein expression suggesting proteolytic activity. 2) Again using in situ hybridization and immunohistochemistry, the investigator will correlate the expression of specific isopeptidases the p27 and p53 protein levels and their ubiquitin mediated degradation. To evaluate the data generated from this aim they have developed specific algorithms for determination of direct relationships(?) between the isopeptidases, p27 and p53. In the final part of this aim, they will use a ubiquitin-mediated degradation assay to measure the potential for p27 and p53 protein degradation. 3) Their final specific aim will be to determine how the overexpression or inhibition of isopeptidases affect apoptosis and/or cell cycle arrest in their androgen-sensitive LNCaP model of apoptosis.